1. Field
Aspects of embodiments according to the present invention relate generally to an organic light emitting diode (OLED) display.
2. Description of the Related Art
An organic light emitting diode (OLED) display includes organic light emitting elements formed of a hole injection electrode, an organic emission layer, and an electron injection electrode. With the OLED display, electrons and holes are combined with each other in the organic emission layer to thereby generate excitons. When the excitons transition from the excited state to the ground state, energy is released so as to emit light, and images are displayed by the emitted light.
An OLED display is a flat panel display which can be made lightweight and thin because it has a self-luminous characteristic and requires no separate light source. Particularly, the OLED display exhibits characteristics such as low power consumption, high luminance, fast response speed, and as such, the OLED display is receiving much attention as a next-generation display device.
The organic light emitting element may deteriorate due to internal and external factors. Regarding the internal factors, the organic emissive layer deteriorates under the atmosphere of oxygen from indium tin oxide (ITO) being the electrode material, or under the interfacial reaction between organic layer components of the organic emissive layer. The external factors include external moisture and oxygen, and ultraviolet ray. In particular, as the external oxygen and moisture may seriously influence the life span of the organic light emitting diode, it is very important to package the organic light emitting diode such that it is sealed from the outside in a vacuum-tight manner.
A thin film encapsulation (TFE) technique may be introduced in packaging the organic light emitting diode, which is well known to those skilled in the art. With the thin film encapsulation technique, one or more of inorganic and organic layers are alternately deposited on the organic light emitting elements formed at the display area of the substrate, thereby covering the display area with a thin film encapsulation layer. With the OLED display with such a thin film encapsulation layer, if the substrate is formed with a flexible film, it can be bent easily, and may form a slim structure.
However, the thin film encapsulation layer is formed by alternately layering a plurality of inorganic layers and a plurality of organic layers, and thus light emitted from an organic emission layer may be wholly or substantially reflected while being passed through the thin film encapsulation layer. Thus, the light emitted from the organic emission layer cannot be emitted to the outside due to the total reflection so that light efficiency is deteriorated.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology, and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.